Asthma

Fact sheet N°307
May 2011

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Key facts
Asthma is a chronic disease of the bronchial, the air passages leading to and from the lungs.
Some 235 million people currently suffer from asthma. It is the most common chronic disease among children.
Most asthma-related deaths occur in low- and lower-middle income countries.
The strongest risk factors for developing asthma are inhaled substances and particles that may provoke allergic reactions or irritate the airways.
Medication can control asthma. Avoiding asthma triggers can also reduce the severity of asthma.
Appropriate management of asthma can enable people to enjoy a good quality of life.

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Asthma is a chronic disease characterized by recurrent attacks of breathlessness and wheezing, which vary in severity and frequency from person to person. Symptoms may occur several times in a day or week in affected individuals, and for some people become worse during physical activity or at night. During an asthma attack, the lining of the bronchial tubes swell, causing the airways to narrow and reducing the flow of air into and out of the lungs. Recurrent asthma symptoms frequently cause sleeplessness, daytime fatigue, reduced activity levels and school and work absenteeism. Asthma has a relatively low fatality rate compared to other chronic diseases.
Facts about asthma
WHO estimates that 235 million people currently suffer from asthma. Asthma is the most common chronic disease among children.
Asthma is a public health problem not just for high-income countries; it occurs in all countries regardless of the level of development. Most asthma-related deaths occur in low- and lower-middle income countries.
Asthma is under-diagnosed and under-treated. It creates substantial burden to individuals and families and often restricts individuals’ activities for a lifetime.


The causes
The fundamental causes of asthma are not completely understood. The strongest risk factors for developing asthma are a combination of genetic predisposition with environmental exposure to inhaled substances and particles that may provoke allergic reactions or irritate the airways, such as:
 indoor allergens (for example, house dust mites in bedding, carpets and stuffed furniture, pollution and pet dander)
outdoor allergens (such as pollens and moulds)
tobacco smoke
chemical irritants in the workplace
air pollution.

Other triggers can include cold air, extreme emotional arousal such as anger or fear, and physical exercise. Even certain medications can trigger asthma: aspirin and other non-steroid anti-inflammatory drugs, and beta-blockers (which are used to treat high blood pressure, heart conditions and migraine).
Urbanization has been associated with an increase in asthma. But the exact nature of this relationship is unclear.
Reducing the asthma burden
Although asthma cannot be cured, appropriate management can control the disease and enable people to enjoy a good quality of life. Short-term medications are used to relieve symptoms. People with persistent symptoms must take long-term medication daily to control the underlying inflammation and prevent symptoms and exacerbations.
Medication is not the only way to control asthma. It is also important to avoid asthma triggers - stimuli that irritate and inflame the airways. With medical support, each asthma patient must learn what triggers he or she should avoid.
Although asthma does not kill on the scale of chronic obstructive pulmonary disease (COPD) or other chronic diseases, failure to use appropriate medications or to adhere to treatment can lead to death.
WHO strategy for prevention and control of asthma
WHO recognizes that asthma is of major public health importance. The Organization plays a role in coordinating international efforts against the disease. The aim of its strategy is to support Member States in their efforts to reduce the disability and premature death related to asthma.

WHO's programme objectives are:
 surveillance to map the magnitude of asthma, analyse its determinants and monitor trends, with emphasis on poor and disadvantaged populations;
primary prevention to reduce the level of exposure to common risk factors, particularly tobacco smoke, frequent lower respiratory infections during childhood, and air pollution (indoor, outdoor, and occupational exposure); and
identifying cost-effective interventions, upgrading standards and accessibility of care at different levels of the health care system.

Global Alliance against Chronic Respiratory Diseases:
The Global Alliance against Chronic Respiratory Diseases (GARD) contributes to WHO’s work to prevent and control chronic respiratory diseases. It is a voluntary alliance of national and international organizations and agencies from many countries. It focuses on the needs of low- and middle-income countries and vulnerable populations, and fosters initiatives that are tailored to local needs.